There are red stars, orange stars, yellow stars, and blue stars. Why no green stars?
A star (or other hot object) emits light across the entire visible spectrum, but the wavelength at which it shines brightest depends on its temperature. Hotter stars emit proportionately more blue light than red; for cooler ones it's the other way around. But no matter where in the spectrum a star's brightness peaks, there's plenty of light coming out at other wavelengths too. So most star colors look pale: that is, white with a slight bluish or orangish cast if they're especially hot or cool, respectively. No stars as are as colorful as, for instance, traffic lights.
The palest-looking of all stars are those that, like our Sun, peak in the green. We, after all, evolved to see mainly by daylight (basically, sunnlight). Our definitive article about this is Philip C. Steffey's "
The Truth About Star Colors" in the September 1992 issue.
— Richard Tresch Fienberg